1. General and Particular Scope of the Invention
The present invention relates in general to wireless network access devices, such as cellular telephones, and methods of alerting a user to an incoming call, and, in particular, in circuitry for monitoring a battery pack that alerts a user to an incoming call on the device without using the device's alarm system.
2. Known Prior Art
Wireless network access devices, such as cellular telephones, mobile facsimile machines and wireless personal assistants, are fast becoming essential business tools appearing everywhere carried by rushed executives needing need to be constantly available. In fact, the very mobility of these devices creates new problems for their users. For example, the annoying sound of a cellular telephone or pager ringing in normally quiet restaurants, concert halls and theaters has led some establishments to ban cellular telephones and pagers from their premises or to require the owners to at least turn the devices off under threat of ejection.
At the other end of the spectrum is the problem where the user has walked a short distance away from the cellular telephone or pager and has missed an incoming call because the device's warning alarm was not loud enough to be heard.
In both of these situations the very mobility of the devices creates problems tending to limit their usefulness and restrict their owners from enjoying the full freedom and mobility the devices promise.
While important embodiment of the invention will be discussed as applied to cellular telephones, wireless network access devices are not restricted to cellular telephones, but also include other access devices for wireless systems, such as the cellular system connecting pagers, modems, facsimile machines and the like, as well as wireless devices operating on the Personal Communications System (PCS), Personal Communications Net (PCN), Global Speciale Mobile (GSM), Specialized Mobile Radio (SMR), Extended Specialized Mobile Radio (ESMR), and other wireless systems.
Using cellular telephones, as an example, as a result of the general disapproval and embarrassment of hearing a cellular telephone ringing in normally quiet areas or at inappropriate times, cellular telephone manufacturers have begun adding to their units non-audible alarms in the form of vibrators and lights to provide their users with a choice between an audible or a silent alarm signaling an incoming call. Some even offer an antenna with a light indicator, such as a LED, that flashes to indicate incoming calls as a visual alarm.
No solution to amplify the alarm of a wireless network access device without modification of the internal circuitry of the device, other than that disclosed in the pending patent applications cited below, is known to Applicants.
Pending patent applications Ser. Nos. 08/400340 filed Mar. 8, 1995 and 08/437,173 filed May 8, 1995, disclose circuitry and methods for detecting incoming calls to a wireless network access device with an externally activated circuit that provides both audible and non-audible alarm systems.